Keith Packard is again serving as the release manager for this next release to come out of the xserver Git code-base. With the consistent six-month release cycle continuing to work out well for delivering timely releases compared to years in the past, this is again being planned for the 1.14 release.
With X.Org Server 1.13 having been released in early September, the X.Org Server 1.14 release is tentatively being planned for 5 March of 2013. The release date might end up changing by a week or so, but Keith and the other X.Org Server developers seem happy with this release plan.
Expected features to land for X.Org Server 1.14 include likely merging XWayland support for running X11 applications with a root-less server on top of Wayland/Weston, the just-planned ideas for DRI3, more GPU hot-plugging work, few GLX improvements, working support for GPU switching, and removing Xinerama support. Keith clarified this morning as well he's already begun drafting the "Direct Rendering Infrastructure 3" changes but that it will likely just be tacking on some new protocol requests to DRI2 rather than a rewrite or causing major breaks.
We'll see what else arrives for X.Org Server 1.14 in the next few months while the merge window is open. XWayland integration should be nice to see along with the continued work by David Airlie on GPU switching/hot-plugging, in addition to the likely killing of Xinerama as a "fix" to the troubled multi-monitor support.